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<title>Qt 4.8: QTextObjectInterface Class Reference</title>
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<a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">QTextObjectInterface Class Reference</h1>
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<p>The QTextObjectInterface class allows drawing of custom text objects in <a href="qtextdocument.html">QTextDocument</a>s. <a href="#details">More...</a></p>
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<pre class="cpp"> <span class="preprocessor">#include <QTextObjectInterface></span></pre><p>This class was introduced in Qt 4.5.</p>
<ul>
<li><a href="qtextobjectinterface-members.html">List of all members, including inherited members</a></li>
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<a name="public-functions"></a>
<h2>Public Functions</h2>
<table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> virtual </td><td class="memItemRight bottomAlign"><b><a href="qtextobjectinterface.html#dtor.QTextObjectInterface">~QTextObjectInterface</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual void </td><td class="memItemRight bottomAlign"><b><a href="qtextobjectinterface.html#drawObject">drawObject</a></b> ( QPainter * <i>painter</i>, const QRectF & <i>rect</i>, QTextDocument * <i>doc</i>, int <i>posInDocument</i>, const QTextFormat & <i>format</i> ) = 0</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> virtual QSizeF </td><td class="memItemRight bottomAlign"><b><a href="qtextobjectinterface.html#intrinsicSize">intrinsicSize</a></b> ( QTextDocument * <i>doc</i>, int <i>posInDocument</i>, const QTextFormat & <i>format</i> ) = 0</td></tr>
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<h2>Detailed Description</h2>
<p>The QTextObjectInterface class allows drawing of custom text objects in <a href="qtextdocument.html">QTextDocument</a>s.</p>
<p>A text object describes the structure of one or more elements in a text document; for instance, images imported from HTML are implemented using text objects. A text object knows how to lay out and draw its elements when a document is being rendered.</p>
<p>Qt allows custom text objects to be inserted into a document by registering a custom <a href="qtextformat.html#objectType">object type</a> with <a href="qtextcharformat.html">QTextCharFormat</a>. A QTextObjectInterface must also be implemented for this type and be <a href="qabstracttextdocumentlayout.html#registerHandler">registered</a> with the <a href="qabstracttextdocumentlayout.html">QAbstractTextDocumentLayout</a> of the document. When the object type is encountered while rendering a <a href="qtextdocument.html">QTextDocument</a>, the <a href="qtextobjectinterface.html#intrinsicSize">intrinsicSize</a>() and <a href="qtextobjectinterface.html#drawObject">drawObject</a>() functions of the interface are called.</p>
<p>The following list explains the required steps of inserting a custom text object into a document:</p>
<ul>
<li>Choose an <i>objectType</i>. The <i>objectType</i> is an integer with a value greater or equal to <a href="qtextformat.html#ObjectTypes-enum">QTextFormat::UserObject</a>.</li>
<li>Create a <a href="qtextcharformat.html">QTextCharFormat</a> object and set the object type to the chosen type using the setObjectType() function.</li>
<li>Implement the QTextObjectInterface class.</li>
<li>Call <a href="qabstracttextdocumentlayout.html#registerHandler">QAbstractTextDocumentLayout::registerHandler</a>() with an instance of your QTextObjectInterface subclass to register your object type.</li>
<li>Insert <a href="qchar.html#SpecialCharacter-enum">QChar::ObjectReplacementCharacter</a> with the aforementioned <a href="qtextcharformat.html">QTextCharFormat</a> of the chosen object type into the document. As mentioned, the functions of QTextObjectInterface <a href="qtextobjectinterface.html#intrinsicSize">intrinsicSize()</a> and <a href="qtextobjectinterface.html#drawObject">drawObject()</a> will then be called with the <a href="qtextformat.html">QTextFormat</a> as parameter whenever the replacement character is encountered.</li>
</ul>
<p>A class implementing a text object needs to inherit both <a href="qobject.html">QObject</a> and QTextObjectInterface. <a href="qobject.html">QObject</a> must be the first class inherited. For instance:</p>
<pre class="cpp"> <span class="keyword">class</span> SvgTextObject : <span class="keyword">public</span> <span class="type"><a href="qobject.html">QObject</a></span><span class="operator">,</span> <span class="keyword">public</span> <span class="type">QTextObjectInterface</span>
{
Q_OBJECT
Q_INTERFACES(<span class="type">QTextObjectInterface</span>)</pre>
<p>The data of a text object is usually stored in the <a href="qtextcharformat.html">QTextCharFormat</a> using <a href="qtextformat.html#setProperty">QTextCharFormat::setProperty</a>(), and then retrieved with <a href="qtextformat.html#property">QTextCharFormat::property</a>().</p>
<p><b>Warning:</b> Copy and Paste operations ignore custom text objects.</p>
</div>
<p><b>See also </b><a href="richtext-textobject.html">Text Object Example</a>, <a href="qtextcharformat.html">QTextCharFormat</a>, and <a href="qtextlayout.html">QTextLayout</a>.</p>
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<h2>Member Function Documentation</h2>
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<h3 class="fn"><a name="dtor.QTextObjectInterface"></a>QTextObjectInterface::<span class="name">~QTextObjectInterface</span> ()<tt> [virtual]</tt></h3>
<p>Destroys this <a href="qtextobjectinterface.html">QTextObjectInterface</a>.</p>
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<h3 class="fn"><a name="drawObject"></a><span class="type">void</span> QTextObjectInterface::<span class="name">drawObject</span> ( <span class="type"><a href="qpainter.html">QPainter</a></span> * <i>painter</i>, const <span class="type"><a href="qrectf.html">QRectF</a></span> & <i>rect</i>, <span class="type"><a href="qtextdocument.html">QTextDocument</a></span> * <i>doc</i>, <span class="type">int</span> <i>posInDocument</i>, const <span class="type"><a href="qtextformat.html">QTextFormat</a></span> & <i>format</i> )<tt> [pure virtual]</tt></h3>
<p>Draws this text object using the specified <i>painter</i>.</p>
<p>The size of the rectangle, <i>rect</i>, to draw in is the size previously calculated by <a href="qtextobjectinterface.html#intrinsicSize">intrinsicSize</a>(). The rectangles position is relative to the <i>painter</i>.</p>
<p>You also get the document (<i>doc</i>) and the position (<i>posInDocument</i>) of the <i>format</i> in that document.</p>
<p><b>See also </b><a href="qtextobjectinterface.html#intrinsicSize">intrinsicSize</a>().</p>
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<h3 class="fn"><a name="intrinsicSize"></a><span class="type"><a href="qsizef.html">QSizeF</a></span> QTextObjectInterface::<span class="name">intrinsicSize</span> ( <span class="type"><a href="qtextdocument.html">QTextDocument</a></span> * <i>doc</i>, <span class="type">int</span> <i>posInDocument</i>, const <span class="type"><a href="qtextformat.html">QTextFormat</a></span> & <i>format</i> )<tt> [pure virtual]</tt></h3>
<p>The intrinsicSize() function returns the size of the text object represented by <i>format</i> in the given document (<i>doc</i>) at the given position (<i>posInDocument</i>).</p>
<p>The size calculated will be used for subsequent calls to <a href="qtextobjectinterface.html#drawObject">drawObject</a>() for this <i>format</i>.</p>
<p><b>See also </b><a href="qtextobjectinterface.html#drawObject">drawObject</a>().</p>
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